Asuka Period, a period known as the first historical period of Japan. Although it's just a cheap cover of a book that hides a heavy history from the public eye.
Asuka Period is when all the exorcists gathered on mountain Nishiyama to seal the great gate of the yokai realm. Then, the imperial court declared to execute all the exorcist clans because they were no longer needed. In just a year, more than hundreds of clans were erased from existence.
But yokai, curse, demons are something that will roam around where humans live. The absence of exorcists greatly impacted humankind.
It was the time when a great war took place and the lasting exorcists started to show up. The powerful clan that was under the protection of the king joined the war but sadly, it was figured out by the enemy.
That time, the Yami clan that used swords to exorcise yokai also disappeared from the earth. It was the end of the era of the exorcist and the beginning of the magicians.
Aori Ito, who was an exorcist in her past life, became a boy in the modern era of Japan. The era where magicians hide from the public, fight yokai and curses to protect everyone.